Dual release circuit for fire protection system

ABSTRACT

A dual release circuit comprises a plurality of pyrotechnic initiators electrically interconnected in series, a plurality of subcircuits electrically interconnected between the pyrotechnic initiators to form at least a first circuit route to electrically interconnect the plurality of pyrotechnic initiators and a second circuit route to electrically interconnect the pyrotechnic initiators, and a control unit electrically connected to the first circuit route and the second circuit route and configured to monitor a first parameter of the first circuit route, monitor a second parameter of the second circuit route, detect when at least one of the first parameter and the second parameter is outside of a specified parameter range, generate an alert indication according to the detection and be able to release the pyrotechnic initiators in response to a release request.

CLAIM OF PRIORITY

This application is a divisional of U.S. patent application Ser. No.13/887,749 (now U.S. Pat. No. 9,092,966) filed on May 6, 2013, whichclaims the benefit of priority under 35 U.S.C. §119(e) of U.S.Provisional Patent Application Ser. No. 61/643,701, titled “DUAL RELEASECIRCUIT,” filed on May 7, 2012, both of which are incorporated herein byreference in their entirety.

TECHNICAL FIELD

This document relates to a dual release circuit and, more specifically,to a dual release actuation circuit in a fire protection circuit.

BACKGROUND

In 2006, the International Maritime Organization (IMO) updated variousfire protection requirements for ships including a clarification of therequirements for monitoring and actuating the extinguishing systems ifthe extinguishing systems are placed inside the compartment (e.g., anengine room) that is being protected from fire.

Traditionally, these systems have been released either throughmechanical pull-cables or by pneumatic means. The use of electricrelease was not prohibited, although no electrical equivalent to thepneumatic methods was available. The concept of a suitable electricalmethod that would satisfy the technical requirements of the IMO andother maritime authorities may be desirable because the installation ofelectrical cable on ships is expected to be less costly than mechanicalor pneumatic methods.

As an example of one regulatory authority, the United States Coast Guard(USCG) originally required all firefighting systems placed outside aspace to be protected in order to insure access to the release methodsand to insure the system is not damaged by being in the space.Eventually, the USCG allowed some systems to be placed in the spaceusing dual circuit pneumatic release methods but, on further evaluation,it was found that the equipment experienced significant failure. Inconsequence, the practice of placing fire protection equipment insidethe protected space is typically considered unreliable and thus thepractice of allowing the fire equipment to be placed in the fire areawas discontinued. Allowing the marine authorities to return to fireequipment placed inside the protected space would require overcomingtheir concerns for the robustness of the equipment and the actuationmethods.

For the foregoing reasons, there is a need for an electrical release fora fire protection system. The dual circuit release described herein willallow more robust equipment that will survive fire and damage. Thismethod provides not only duplicated release but also providessupervision to annunciate or otherwise indicate a potential loss ofcapability before the loss of capability happens. The proposed dualcircuit release will provide the opportunity to detect and correctfaults to ensure the on-going robustness of the system.

OVERVIEW

Embodiments relate to a dual release circuit, actuation circuit andmethod of operating a dual release circuit and actuation circuit. Moreparticularly, the invention relates to a dual release circuit actuationin a fire protection circuit. Some embodiments relate to at least twocircuits that are monitored for faults so that a single fault will notprevent circuit actuation. Embodiments can include a series circuitapproach results in the lowest possible current.

Embodiments can provide increased reliability over present methods, andlower the cost of the actuation method, the equipment being actuated,and the cost of installation. This allows the adoption of new fireextinguishing technology (aerosols) where the containers may be placedwithin a protected space and placed on ceilings and walls to minimizespace requirements.

Embodiments of the proposed dual release circuit allow for more robustequipment that will survive fire and damage. This method provides fornot only duplicated release but also provides supervision to indicate apotential loss of capability before the actual loss of capabilityoccurs. The proposed dual circuit release will provide the opportunityto correct faults and thus insure the on-going robustness of the system.

Embodiments of a fire protection actuation system focus on reliabilityand the ability to survive damage. The circuits can be duplicated andmonitored. The monitoring includes supervision through the initiators.The monitoring can indicate a fault that can be corrected. In the eventof a deteriorated state (any first fault such as a short or opencircuit), the system will retain its full ability to function and activethe initiators.

Embodiments relate to a dual release circuit, actuation circuit andmethod of operating a dual release circuit and actuation circuit. Anexample of the dual release circuit includes a plurality of pyrotechnicinitiators electrically interconnected in series, a plurality ofsubcircuits electrically interconnected between the pyrotechnicinitiators to form at least a first circuit route to electricallyinterconnect the plurality of pyrotechnic initiators and a secondcircuit route to electrically interconnect the pyrotechnic initiators,and a control unit electrically connected to the first circuit route andthe second circuit route. The control unit is configured to monitor afirst parameter of the first circuit route, monitor a second parameterof the second circuit route, detect when at least one of the firstparameter and the second parameter is outside of a specified parameterrange, and generate an alert indication according to the detection.

An example of a fire protection actuation circuit includes a pluralityof pyrotechnic initiators electrically interconnected in series, aplurality of subcircuits electrically interconnected between thepyrotechnic initiators to form a first circuit route to electricallyinterconnect the plurality of pyrotechnic initiators and a secondcircuit route to electrically interconnect the pyrotechnic initiators,and a control unit electrically connected to the first circuit route andthe second circuit route. A pyrotechnic initiator can be included in anignition unit of a fire extinguishing assembly. The control unit can beconfigured to monitor a first parameter of the first circuit route,monitor a second parameter of the second circuit route, detect when atleast one of the first parameter and the second parameter is outside ofa specified parameter range, generate an alert indication according tothe detection, and apply, in response to a release request, a releasecurrent to the pyrotechnic initiators using at least one of the firstcircuit route or the second circuit route.

An example of a method of operating a dual release circuit includesmonitoring, in a supervisory mode, a first circuit route and a secondcircuit route. The first circuit route and the second circuit routeinclude a plurality of sub-circuits electrically interconnected to aplurality of pyrotechnic initiators. The monitoring can includemonitoring a first parameter of the first circuit route and a secondparameter of the second circuit route, detecting that at least one ofthe first parameter or the second parameter is outside of a specifiedparameter range, and generating an alert indication in response to thedetecting.

The foregoing and other features and advantages of the invention willbecome further apparent from the following detailed description of thepresently preferred embodiment, read in conjunction with theaccompanying drawings. The drawings are not to scale. The detaileddescription and drawings are merely illustrative of the invention ratherthan limiting, the scope of the invention being defined by the appendedclaims and equivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, the various examples discussed in the presentdocument.

FIG. 1 illustrates portions of an example of a dual release circuit.

FIGS. 2A and 2B illustrate an example of supervision mode of a dualrelease circuit.

FIGS. 3A and 3B illustrate portions of an example of a release mode ofthe dual release circuit.

FIG. 4 shows a diagram of an example of a dual release circuit with acontrol unit.

FIG. 5 shows a diagram of portions of another example of a fireprotection system.

FIG. 6 illustrates portions of another example of a dual releasecircuit.

FIG. 7 illustrates portions of still another example of a dual releasecircuit.

FIGS. 8A and 8B illustrate an example of a dual release circuitoperating in a supervision mode.

FIGS. 9A and 9B illustrate an example of a dual release circuitoperating in a release mode.

FIGS. 10A and 10B illustrate an example of a dual release circuitoperating in a line check mode.

FIG. 11 shows a diagram of an example of a constant current dual releasecircuit with a control unit.

FIG. 12 shows a diagram of portions of another example of a fireprotection system.

FIG. 13 shows a flow diagram of a method 1300 of operating a dualrelease circuit.

DETAILED DESCRIPTION

Embodiments relate to a circuit based activation of safety equipment.Embodiments related to electrically release (activation) a series ofpyrotechnic initiators. These initiators, in-turn, will performactivities such as the release of fire extinguishing systems, performingoperations such as stopping/starting equipment, opening/closing doors,etc. The Dual-Release Circuit illustrated in FIG. 1 provides a releasemethod that monitors the circuit for reliability so that a fault, suchas an open circuit caused by a broken wire, can be annunciated orotherwise indicated. The release is to also survive any single fault sothat it will provide the release of all the pyrotechnic initiators evenif there has been a fault.

Pyrotechnic initiators can be used to actuate fireworks, explosives formilitary/demolition/mining application, safety devices for military(aircraft canopy ejection, etc.). These devices may need a certain levelof energy input that can be an electrical current applied over a giventime with a typical “guaranteed release energy” for a device being 1 ampover 100 milliseconds. Additionally, a very low trickle current (e.g., 3to 25 milliamps) can be applied to the pyrotechnic initiators formonitoring to confirm the device is in place and therefore available foractuation. The circuits may be in series or in parallel with the seriesapproach being the most common route because, not only is it the moresimple arrangement, but also the current needed is lower than theparallel methods. When actuated, the initiators can be used to triggerother devices, such as a fire extinguishing unit. Actuation of theinitiators may create either an open or a short at that point, but theuseful feature is that all the devices will have received sufficientenergy to actuate simultaneously in advance of their failure to an openor short being significant.

For a simple series circuit with no backup, the technician or theequipment to release the circuit performs a simple circuit check toconfirm continuity, and any faults are detected and corrected manuallyin advance of the release of the initiators. A better approach is toimplement an activation circuit with multiple initiators that are“survivable” (e.g., tolerant to damage or failure). Fire alarm systemsmay use supervised circuits for both the detection of fire and for thesignals to release the extinguishing systems. The release circuits aretypically operating solenoids because pyrotechnic initiators or “squib”devices have explosive classification. These solenoid-based releasecircuits are frequently supervised so that a fault (an “open”) isannunciated but the fault must be repaired for the extinguishing systemto function and release fire retardant material. These types of circuitsthat are not fault tolerant are commonly referred to as Class Bcircuits. More advanced circuits are Class A circuits that monitor forfaults (which may both opens and shorts) and, while annunciating thefault, the circuit will still retain full functionality. Typically,solenoid-based class A circuit use a parallel circuit topology; leadingto higher cost. The supervision is typically for circuit wires and notfor the actuating devices (e.g., the solenoids) themselves. Theembodiments described herein use multiple pyrotechnic initiators insteadof solenoids to implement a Class A fire alarm circuit and arrange thepyrotechnic initiators in series.

Typical fire alarm release circuits can be similar to circuits used tosound a fire alarm bell. Typically, these are parallel circuits thatgenerally do not provide supervision through the bell or releasesolenoid. Supervision of series circuits is accomplished by supplying atrickle current through the wire with the current limited by anend-of-line resistor. The alarm unit monitors the circuit to insure thatthe small current confirms the circuit is intact. In a typical firealarm system, this supervision current does not go through the alarmdevices or release devices.

FIG. 1 illustrates portions of an example of a dual release circuit 100.The dual release circuit 100 includes a plurality of pyrotechnicinitiators 105A, 105B, 105C. The pyrotechnic initiators are arranged inseries and the example has a quantity of initiators numbered 1 to N,where N is positive integer greater than 1. In the example shown, afirst circuit route 110 (side A) and a second circuit route 115 (side B)electrically interconnects the pyrotechnic initiators to create acircuit with redundancy. Each pyrotechnic initiator can be electricallyactivated by two circuit routes so that physical damage to one circuitroute, which would typically result in a broken wire or a short, willnot prevent the release of all the initiators. Additional circuit routesmay be included to increase circuit redundancy.

Both release circuit routes can be supervised with trickle currents sothat an open or short circuit can be detected. The dual release circuit100 may have four states: Supervision Side-A/First Side, SupervisionSide-B/Second Side, Release Side-A/First Side, and Release Side-B/SecondSide. A control unit (shown in FIG. 4) can be electrically connected tothe first circuit route and a second circuit route to control the stateof the dual release circuit 100. In Supervision Mode, the control unitmonitors a first parameter of the first circuit route 110 and a secondparameter of the second circuit route 115. When the control unit detectsthat at least one of the first parameter and the second parameter isoutside a specified (e.g., programmed) range, the control unit maygenerate an alert indication (e.g., an alerting signal provided to aprocess, or an audio or visual indication provided to a user).

FIG. 2A illustrates an example of Supervision Side-A/First Side. Thefirst circuit route 210 and the second circuit route 215 may include anend of line circuit 220. The end of line circuit shown includes aresistive divider circuit and a diode. In this supervision mode, thecontrol unit may apply a constant voltage to the first circuit route210, and monitor the current flowing through the first circuit route 210from Side-A as the first parameter. In some examples, the control unitmonitors a trickle direct current (DC) from Side-A while Side B is off.The value of the constant voltage applied and the resistance of theresistive divider circuit determines the trickle current used forsupervision. If the monitored current is in the expected normal range,the circuit is considered as “normal” and the circuit is turned off andthen Side-B may be turned on. If the monitored current is not within theexpected range, the control unit may generate an alert indication toannunciate the condition and may then proceed to the supervision ofSide-B/Second Side.

FIG. 2B illustrates an example of Supervision Side-B/Second Side. Inthis supervision mode, the control unit may apply a constant voltage tothe second circuit route 215, and monitor the current flowing throughthe second circuit route 215 from Side-B as the second parameter. If themonitored current is in the expected range, the circuit is considered“normal” and the circuit is turned off and Side-A may again be turned onand the supervision can be repeated in a cycle. If the monitored currentfor Side-B is not within the expected range, the control unit maygenerate an alert indication to annunciate the condition and may thenproceed to the supervision of Side-A/First Side. The repetitive cyclefor monitoring of the dual release circuit may be repeated recurrently(e.g., continuously or according to a schedule). In supervision mode,the control unit may cycle between Side-A and Side-B with one side beingon while the other side is off.

FIG. 3A illustrates an example of Release Side-A/First Side. When therelease of the pyrotechnic initiators 305A, 305B, and 305C is required,the control unit may enter a release mode. In the example of FIG. 3A,the control unit may apply a constant voltage with a polarity differentfrom the supervision mode. This reversed polarity results in a currentreversed from the monitoring current to flow through the first circuitroute 310. The release current flowing in the first circuit route 310passes through the diode of the end of line circuit 320. Becauseactivation of the diode reduces the resistance in the first circuitroute, the release current is higher than the monitoring current used insupervision mode. The level or magnitude of the release current and theduration of the release current will provide the energy to ignite theseries of pyrotechnic initiators.

FIG. 3B illustrates an example of Release Side-B/Second Side. In therelease mode, the control unit may cycle between Release Side-A/FirstSide and Release Side-B/Second Side. In Release Side-B/Second Side,Side-A may be turned off after a specified duration and Side-B may beturned on with polarity of the applied voltage also reversed and theprocess of providing energy to the pyrotechnic initiators is repeated.The repetitive releasing cycle may be continued for a sufficient numberof cycles (e.g., between Side-A and Side-B) to provide reasonableassurance that the system has released. The control unit can providemonitoring to detect any circuit failure (e.g., a circuit open or ashort) so that an alert indication can be generated. The cycling duringrelease mode may overcome any single first fault in order to provideadequate energy to activate all of the pyrotechnic initiators in thedual release circuit. Additional circuit routes can be added (e.g., atriple release circuit, etc.) to increase the robustness of the releasecircuit.

FIG. 4 shows a diagram of an example of a dual release circuit 400 witha control unit 425. The control unit 425 can provide electrical power,cycle timing and monitoring of faults for supervision mode, and thecycle timing and polarity reversal for release mode. To conserve energy,the control unit 425 may pulse the release current (e.g., a circuitpulse of 1 amp for 1/16^(th) of a second). The control unit 425 mayinclude a port 430 to receive a release request. The control unit 425initiates application of the release current to at least one of thefirst circuit route 410 or the second circuit route 415 in response toreceiving the release request. In some examples, the dual releasecircuit 400 is included in a fire protection system that is useractivated and the release request can be received from a user activationinterface. In some examples, the dual release circuit 400 is included ina fire protection system for marine use.

FIG. 5 shows a diagram of portions of another example of a fireprotection system. The system includes a dual release circuit 500, acontrol unit 525 and a fire detection unit 535. The fire detection unit535 may include one or more sensors to detect a fire. The control unit525 includes a port 530 to receive the release request from the firedetection unit 535 in response to the fire detection unit 535 detectingan indication of a fire. The dual release circuit 500 may includeelectrical devices to condition the dual release circuit againstunwanted electrical spikes that could result in false release of any orall of the pyrotechnic initiators. The control unit 525 and firedetection unit 535 may be part of a larger system that is capable ofproviding multiple release circuits to increase the size of the numberof similar initiator actuation circuits in the system (e.g., C1, C2, . .. CN), and may include additional power supplies, fire detection units,control units, and include annunciation and display capabilities.

FIG. 6 illustrates portions of another example of a dual release circuit600. The dual release circuit 600 again includes a plurality ofsubcircuits electrically interconnected between the pyrotechnicinitiators to form a first circuit route 610 and a second circuit route615. In this example, the subcircuits include resistors as well asdiodes. In some examples, the resistors (R₁) arranged in parallel withthe pyrotechnic initiators may instead be diodes. In a supervision mode,a control unit (not shown) applies a first constant monitoring voltageto the first circuit route, apply a second constant monitoring voltageto the second circuit route, and monitor a first current flowing throughthe first circuit route as the first parameter and monitor a secondcurrent flowing through the second circuit route as the secondparameter. The first circuit route 610 and the second circuit route 615include an end of line circuit 620. In a release mode, the control unitmay reverse the polarity of the voltage at terminals of one or both thecircuit routes. This causes the diode in the end of line circuit tobecome active and changes the current flowing through the circuit routesto activate the pyrotechnic initiators.

FIG. 7 illustrates portions of still another example of a dual releasecircuit 700. The dual release circuit 700 again includes a plurality ofsubcircuits electrically interconnected between the pyrotechnicinitiators to form a first circuit route 710 and a second circuit route715. However, note that the example shown does not include an end ofline circuit. In supervision mode, the control unit applies a firstconstant monitoring current (instead of voltage) to the first circuitroute 710 and applies a second constant monitoring current to the secondcircuit route 715. In response to applying the constant monitoringcurrents, the control unit monitors a first voltage at terminals of thefirst circuit route 710 as the first parameter and monitors a secondvoltage at terminals of the second circuit route 715 as the secondparameter.

FIGS. 8A and 8B illustrate an example of a dual release circuit 800operating in a supervision mode. FIG. 8A illustrates an example ofSupervision Side-A/First Side. The control unit applies a constantcurrent of low magnitude to the first circuit route 810 and monitors theresulting voltage at the Side-A terminals. The constant current isapplied with one or both of a magnitude and duration to ensure that thepyrotechnic initiators are not released. If the monitored voltage forSide-A is not the expected value or within the expected range, thecontrol unit may generate an alert condition. The control unit may thenproceed to the supervision of Side-B/Second Side. FIG. 8B illustrates anexample of Supervision Side-B/Second Side. The control unit applies aconstant current of low magnitude to the second circuit route 815 andmonitors the resulting voltage at the Side-B terminals. As shown in theexample in the Figure, the monitoring current may be applied to thesecond circuit route 815 in a different direction from the first circuitroute 810 (e.g., the monitoring current may be applied to different endsof the series of subcircuits). If the monitored voltage for Side-B isnot the expected value, or is not within the expected range, the controlunit may generate an alert condition. The control unit may then proceedto the supervision of Side-A/First Side. The control unit maycontinuously cycle between supervision of the first circuit route 810and the second circuit route 815, or may alternately initiate themonitoring of the first and second circuit routes according to aschedule.

FIGS. 9A and 9B illustrate an example of a dual release circuitoperating in a release mode. FIG. 9A illustrates an example of ReleaseSide-A/First Side. The control unit enters release mode when the releaseof the pyrotechnic initiators is required. In the release mode, thecontrol unit may apply a release current to at least one of the firstcircuit route 910 and the second circuit route 915. The release currenthas a higher or greater magnitude than the magnitude of monitoringcurrent used in the supervision mode. The magnitude of the releasecurrent and the duration of the release current will provide the energyto ignite the series of pyrotechnic initiators. In the example shown,the release current is applied in the same direction as the monitoringcurrent during supervision mode, but the control unit may apply therelease current in a different direction from the monitoring current ofsupervision mode. FIG. 9B illustrates an example of ReleaseSide-B/Second Side. The control unit may cycle between ReleaseSide-A/First Side and Release Side-B/Second Side in the release mode.During Release Side-B/Second Side, Side-A may be turned off after aspecified duration and Side-B may be turned on. The cycling may becontinued in release mode for a sufficient number of cycles (e.g.,between Side-A and Side-B) to provide reasonable assurance that thesystem has released.

FIGS. 10A and 10B illustrate an example of a dual release circuit 1000operating in a line check mode. The line check mode is similar tosupervision mode and is executed to confirm that one or more of thefirst circuit route 1010 and the second circuit route 1015 are operable.In the line check mode, a line check is recurrently applied to the firstcircuit route 1010 and the second circuit route 1015. The line checkcurrent is applied in a direction opposite of the release current, andthe magnitude of the line check current is insufficient to ignite theplurality of pyrotechnic initiators. The line check current can bepulsed to conserve energy.

FIG. 11 shows a diagram of an example of a constant current dual releasecircuit 1100 with a control unit 1125. The control unit 1125 can provideelectrical power, cycle timing and monitoring of faults for supervisionmode, release mode, and line check mode. The control unit 1125 mayinclude a port 1130 to receive a release request, such as from a useractivation unit or a fire detection unit.

FIG. 12 shows a diagram of portions of another example of a fireprotection system. The system includes a constant current dual releasecircuit 1200, a control unit 1225 and a fire detection unit 1235. Thefire detection unit 1235 may include one or more sensors to detect afire. The control unit 1225 includes a port 1230 to receive the releaserequest from the fire detection unit 1235 in response to the firedetection unit 1235 detecting an indication of a fire. The system mayinclude multiple release circuits to increase the size of the number ofsimilar initiator actuation circuits in the system (e.g., C1, C2, CN),and may include additional power supplies, fire detection units, controlunits, and include audio and display capabilities to provide alerts oran indication of the location of a detected fault.

FIG. 13 shows a flow diagram of a method 1300 of operating a dualrelease circuit. At block 1305, a first circuit route and a secondcircuit route are monitored in a supervisory or supervision mode. Thefirst circuit route and the second circuit route include a plurality ofsub-circuits electrically interconnected to a plurality of pyrotechnicinitiators. The monitoring may include monitoring a first parameter ofthe first circuit route (e.g., one or more of voltage, current, orresistance) and a second parameter of the second circuit route. At block1310, at least one of the first parameter or the second parameter isdetected to being not equal to a specified parameter value, or isoutside of a specified parameter value range. At block 1315, an alertindication is generated in response to the detection. In some examples,the method 1300 includes at block 1320 receiving a release request atthe dual release circuit. The release request can be in the form of anelectrical signal received from a user activation interface or a firedetection unit. At block 1325, a release mode is initiated in the dualrelease circuit in response to receiving the release request.

The proposed methods and electric arrangements described providesupervision, not only of the electrical wires to the fire protectioncontainers, but also provide supervision through the pyrotechnicinitiators to confirm that it is operable and thus available. The fireprotection system may identify a problem (e.g., a break in a wire) andstill retain full release capability. With the fire extinguishing systemcontainers being placed in the compartment that can suffer fire anddamage, robustness is a major issue. A robust and reliable actuationmethod for fire protection is desirable. The USCG and other marineauthorities may be more willing to accept new extinguishing technologiesand installation methods provided that the systems include monitoring ofactuation, are tolerant to damage, and are generally considered reliablefor the application. The electric dual release circuit approach is animprovement over the traditional pneumatic methods.

The embodiments described herein may reduce the need to pipe theextinguishing agent to the compartment of concern from a separatecompartment and thus save significantly on installation costs. With themethods of electric actuation described, both the equipment that can beinstalled in the space and the cost of installation of the equipmentwill be greatly reduced in cost. This is because it is much easier andfaster to install electric cable than to install pipe and pneumaticsystems. Because there is no need for a large separate compartmentoutside to store the extinguishing equipment, less space may be requiredif fire extinguishing systems can be installed as a distributed systeminside a protected machinery space with the containers placed on thewalls and ceilings of the space. This frees up the deck space (realestate) on a ship for other useful purposes and also removes the cost ofconstructing the separate compartment.

An alternative method to the proposed dual release circuit would be tomake the fire extinguishing containers with two electric/pyrotechnicactuators built inside instead of one so that two standard fire alarmreleasing circuits could be used. However, this would add to the cost ofthe equipment and it would mean that the equipment being released wouldhave to be re-tested by Underwriters' Laboratories at significant cost.Another alternative would be to use duplicated pneumatic circuits as perthe traditional marine practice. The circuits for such an approach wouldbe unsupervised and the level of reliability would be significantlyless. Additionally, the pneumatic route may require duplicated gassources, valves, etc. which adds significant complexity. Yet anotheralternative would be to run parallel circuits to each of the fireextinguishing containers. This may require much higher currents andsignificantly increase installation costs. A failure of one circuitwould likely result in the inability to release one fire extinguishingcontainer, and thus additional containers may be needed at additionalcost to accomplish the same level reliable release all of theextinguishing agent. Further alternative approaches involve continuingto install the fire protection containers outside the space at muchhigher cost, installing fire protection systems offering lowerperformance to obtain lower cost, and installing mechanical cable pulls.These alternative approaches may limit the number of containers that canbe released. Because the actuator cables can extend through long lengthsof pipe or tubes, and have numerous pulleys and bends, it can bephysically difficult to pull a cable with sufficient force for manualrelease.

Additional Notes and Examples

Example 1 can include subject matter (such as an apparatus or dualcircuit) comprising a plurality of pyrotechnic initiators electricallyinterconnected in series, a plurality of subcircuits electricallyinterconnected between the pyrotechnic initiators to form at least afirst circuit route to electrically interconnect the plurality ofpyrotechnic initiators and a second circuit route to electricallyinterconnect the pyrotechnic initiators, and a control unit electricallyconnected to the first circuit route and the second circuit route andconfigured to monitor a first parameter of the first circuit route,monitor a second parameter of the second circuit route, detect when atleast one of the first parameter and the second parameter is outside ofa specified parameter range, and generate an alert indication accordingto the detection.

In Example 2, the subject matter of Example 1 can optionally include acontrol unit that includes a port configured to receive a releaserequest, and wherein the control unit is configured to initiateapplication of a release current to at least one of the first circuitroute and the second circuit route in response to the release request,wherein the release current is configured to ignite the pyrotechnicinitiators.

In Example 3, the subject matter of Example 2 can optionally include aport configured to receive the release request from a fire detectionunit.

In Example 4, the subject matter of one or any combination of Examples 2and 3 can optionally include a port configured to receive the releaserequest from a user activation interface.

In Example 5, the subject matter of one or any combination of Examples1-4 can optionally include a control unit configured to apply a firstconstant monitoring current to the first circuit route, apply a secondconstant monitoring current to the second circuit route, and monitor afirst voltage at terminals of the first circuit route as the firstparameter and monitor a second voltage at terminals of the secondcircuit route as the second parameter.

In Example 6, the subject matter of one or any combination of Examples1-4 can optionally include a control unit configured to apply a firstconstant monitoring voltage to the first circuit route, apply a secondconstant monitoring voltage to the second circuit route, and monitor afirst current flowing through the first circuit route as the firstparameter and monitor a second current flowing through the secondcircuit route as the second parameter.

In Example 7, the subject matter of Examples 6 can optionally include afirst circuit route and a second circuit route that includes an end ofline circuit that includes a resistive divider circuit.

In Example 8, the subject matter of one or any combination of Examples1-7 can optionally include a subcircuit includes at least one diodeelectrically connected to a pyrotechnic initiator.

Example 9 can include subject matter (such as a system or fireprotection actuation circuit) or can optionally be combined with thesubject matter of one or any combination of Examples 1-13 to includesubject matter, comprising a plurality of pyrotechnic initiatorselectrically interconnected in series, wherein a pyrotechnic initiatoris included in an ignition unit of a fire extinguishing assembly, aplurality of subcircuits electrically interconnected between thepyrotechnic initiators to form a first circuit route to electricallyinterconnect the plurality of pyrotechnic initiators and a secondcircuit route to electrically interconnect the pyrotechnic initiators,and a control unit electrically connected to the first circuit route andthe second circuit route. The control unit can optionally be configuredto monitor a first parameter of the first circuit route, monitor asecond parameter of the second circuit route, detect when at least oneof the first parameter and the second parameter is outside of aspecified parameter range, generate an alert indication according to thedetection, and apply, in response to a release request, a releasecurrent to the pyrotechnic initiators using at least one of the firstcircuit route or the second circuit route.

In Example 10, the subject matter of Example 9 can optionally include acontrol unit configured to apply a first constant monitoring current tothe first circuit route, apply a second constant monitoring current tothe second circuit route, monitor a first voltage at terminals of thefirst circuit route as the first parameter and monitor a second voltageat terminals of the second circuit route as the second parameter.

In Example 11, the subject matter of Example 9 optionally includes acontrol unit configured to apply a first constant voltage to the firstcircuit route, apply a second constant voltage to the second circuitroute, and monitor a first current flowing through the first circuitroute as the first parameter and monitor a second current flowingthrough the second circuit route as the second parameter.

In Example 12, the subject matter of one or any combination of Examples9-11 optionally includes release current having a current magnitudevalue greater than a current magnitude value of both the first constantmonitoring current and the second constant monitoring current.

In Example 13, the subject matter of one or any combination of Examples9-12 optionally includes a fire detection unit. The control unit canoptionally be configured to receive the release request from the firedetection unit.

In Example 14, the subject matter of one or any combination of Examples9-13 optionally includes a user activation interface. The control unitcan optionally be configured to receive the release request from theuser activation interface.

In Example 15, the subject matter of one or any combination of Examples9-14 optionally includes control unit configured to alternately initiatethe monitoring of the first parameter of the first circuit route and themonitoring of the second parameter of the second circuit route.

Example 16 can include subject matter (such as a method, a means forperforming acts, or a machine readable medium including instructionsthat, when performed by the machine, that can cause the machine toperform acts), or can optionally be combined with the subject matter ofone or any combination of Examples 1-15 to include subject matter,comprising monitoring, in a supervisory mode, a first circuit route anda second circuit route, wherein the first circuit route and the secondcircuit route include a plurality of sub-circuits electricallyinterconnected to a plurality of pyrotechnic initiators, and wherein themonitoring includes monitoring a first parameter of the first circuitroute and a second parameter of the second circuit route, detecting thatat least one of the first parameter or the second parameter is outsideof a specified parameter range, and generating an alert indication inresponse to the detecting.

In Example 17, the subject matter of Example 16 can optionally includereceiving a release request, and applying, in a release mode, a releasecurrent to at least one of the first circuit or the second circuit routein response to the release indication, wherein the release current isconfigured to ignite the plurality of pyrotechnic initiators.

In Example 18, the subject matter of one or any combination of Examples16 and 17 optionally includes applying a first constant monitoringcurrent to the first circuit route and applying a second constantmonitoring current to the second circuit route, and wherein monitoring afirst parameter of the first circuit route and a second parameter of thesecond circuit route includes monitoring a first voltage at terminals ofthe first circuit route as the first parameter and monitoring a secondvoltage at terminals of the second circuit route as the secondparameter.

In Example 19, the subject matter of one or any combination of Examples16 and 17 optionally includes recurrently applying, in a line checkmode, a line check current to the first circuit and the second circuitroute in a direction opposite of the release current, wherein a currentmagnitude of the line check current is insufficient to ignite theplurality of pyrotechnic initiators, and applying, in a release mode, arelease current to at least one of the first circuit or the secondcircuit route, wherein a current magnitude of the release current issufficient to ignite the plurality of pyrotechnic initiators.

In Example 20, the subject matter of one or any combination of Examples16, 17 and 19 optionally includes including applying a first constantmonitoring voltage to the first circuit route, applying a secondconstant monitoring voltage to the second circuit route, and whereinmonitoring a first parameter of the first circuit route and a secondparameter of the second circuit route includes monitoring a firstcurrent flowing through the first circuit route as the first parameterand monitoring a second current flowing through the second circuit routeas the second parameter.

Example 21 can include, or can optionally be combined with any portionor combination of any portions of any one or more of Examples 1-20 toinclude, subject matter that can include means for performing any one ormore of the functions of Examples 1-20, or a machine-readable mediumincluding instructions that, when performed by a machine, cause themachine to perform any one or more of the functions of Examples 1-20.

Each of these non-limiting examples can stand on its own, or can becombined in various permutations or combinations with one or more of theother examples.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” All publications, patents, and patent documentsreferred to in this document are incorporated by reference herein intheir entirety, as though individually incorporated by reference. In theevent of inconsistent usages between this document and those documentsso incorporated by reference, the usage in the incorporated reference(s)should be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In the appended claims, the terms “including” and“in which” are used as the plain-English equivalents of the respectiveterms “comprising” and “wherein.” Also, in the following claims, theterms “including” and “comprising” are open-ended, that is, a system,device, article, or process that includes elements in addition to thoselisted after such a term in a claim are still deemed to fall within thescope of that claim. Moreover, in the following claims, the terms“first,” “second,” and “third,” etc. are used merely as labels, and arenot intended to impose numerical requirements on their objects. Methodexamples described herein can be machine or computer-implemented atleast in part.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A fire protection actuation circuit comprising: aplurality of pyrotechnic initiators electrically interconnected inseries, wherein a pyrotechnic initiator is included in an ignition unitof a fire extinguishing assembly; a plurality of subcircuitselectrically interconnected between the pyrotechnic initiators to form afirst circuit route to electrically interconnect the plurality ofpyrotechnic initiators and a second circuit route to electricallyinterconnect the pyrotechnic initiators; and a control unit electricallyconnected to the first circuit route and the second circuit route andconfigured to: monitor a first parameter of the first circuit route;monitor a second parameter of the second circuit route; detect when atleast one of the first parameter and the second parameter is outside ofa specified parameter range; generate an alert indication according tothe detection; and apply, in response to a release request, a releasecurrent to the pyrotechnic initiators using at least one of the firstcircuit route or the second circuit route.
 2. The fire protectionactuation circuit of claim 1, wherein the control unit is configured toapply a first constant monitoring current to the first circuit route,apply a second constant monitoring current to the second circuit route,monitor a first voltage at terminals of the first circuit route as thefirst parameter and monitor a second voltage at terminals of the secondcircuit route as the second parameter.
 3. The fire protection actuationcircuit of claim 1, wherein the control unit is configured to apply afirst constant voltage to the first circuit route, apply a secondconstant voltage to the second circuit route, and monitor a firstcurrent flowing through the first circuit route as the first parameterand monitor a second current flowing through the second circuit route asthe second parameter.
 4. The fire protection actuation circuit of claim1, wherein the release current has a current magnitude value greaterthan a current magnitude value of both the first constant monitoringcurrent and the second constant monitoring current.
 5. The fireprotection actuation circuit of claim 1, including a fire detectionunit, wherein the control unit is configured to receive the releaserequest from the fire detection unit.
 6. The fire protection actuationcircuit of claim 1, including a user activation interface, wherein thecontrol unit is configured to receive the release request from the useractivation interface.
 7. The fire protection actuation circuit of claim1, wherein the control unit is configured to alternately initiate themonitoring of the first parameter of the first circuit route and themonitoring of the second parameter of the second circuit route.
 8. Amethod comprising: monitoring, in a supervisory mode, a first circuitroute and a second circuit route, wherein the first circuit route andthe second circuit route include a plurality of sub-circuitselectrically interconnected to a plurality of pyrotechnic initiators,and wherein the monitoring includes monitoring a first parameter of thefirst circuit route and a second parameter of the second circuit route;detecting that at least one of the first parameter or the secondparameter is outside of a specified parameter range; and generating analert indication in response to the detecting.
 9. The method of claim 8,including: receiving a release request; and applying, in a release mode,a release current to at least one of the first circuit or the secondcircuit route in response to the release indication, wherein the releasecurrent is configured to ignite the plurality of pyrotechnic initiators.10. The method of claim 8, including applying a first constantmonitoring current to the first circuit route and applying a secondconstant monitoring current to the second circuit route, and whereinmonitoring a first parameter of the first circuit route and a secondparameter of the second circuit route includes monitoring a firstvoltage at terminals of the first circuit route as the first parameterand monitoring a second voltage at terminals of the second circuit routeas the second parameter.
 11. The method of claim 8, including:recurrently applying, in a line check mode, a line check current to thefirst circuit and the second circuit route in a direction opposite ofthe release current, wherein a current magnitude of the line checkcurrent is insufficient to ignite the plurality of pyrotechnicinitiators; and applying, in a release mode, a release current to atleast one of the first circuit or the second circuit route, wherein acurrent magnitude of the release current is sufficient to ignite theplurality of pyrotechnic initiators.
 12. The method of claim 8,including applying a first constant monitoring voltage to the firstcircuit route, applying a second constant monitoring voltage to thesecond circuit route, and wherein monitoring a first parameter of thefirst circuit route and a second parameter of the second circuit routeincludes monitoring a first current flowing through the first circuitroute as the first parameter and monitoring a second current flowingthrough the second circuit route as the second parameter.